<%@ page import="java.util.ArrayList" %>
<%@ page import="java.util.HashMap" %><%--
  Created by IntelliJ IDEA.
  User: ZhuoWen
  Date: 2022/4/24
  Time: 10:03
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
</head>
<body>
<%
//    1、值为 null 值的时候，为空
    request.setAttribute("emptyNull",null);
//    2、值为空串的时候，为空
    request.setAttribute("emptyString","");
//    3、值是 Object 类型数组，长度为零的时候
    request.setAttribute("emptyArray",new Object[]{});
//    4、list 集合，元素个数为零
    request.setAttribute("emptyList",new ArrayList<>());
//    5、map 集合，元素个数为零
    request.setAttribute("empeyMap",new HashMap<String,Object>());
%>
    ${empty emptyNull}<br>
    ${empty emptyString}<br>
    ${empty emptyArray}<br>
    ${empty emptyList}<br>
    ${empty empeyMap}<br>
    ${12>12?"12大于12":"12不大于12"}
</body>
</html>
